FAST PHOTOLUMINESCENCE DECAY IN A-SIH

Photoluminescence (PL) decay in a-Si:H has been measured in the 0.1 - to 50-ns range, and the dependence upon temperature, emission energy, excitation energy, and electric field has been systematically investig ated. A fast analog technique with a time resolution of 100 ps was use d for the measurements. We present a method for quantitatively charact erizing the PL decay in terms of a model function, with which the expe rimental time broadening is removed by deconvolution. The model functi on is I(t) = a0 + SIGMA(i = 1)n a(i)exp( - t/tau(i)), where a0, a(i), and tau(i) are the fitting parameters. These fits yield three distinct lifetimes: tau1 = 0.8 +/- 0.2 ns, tau2 = 3.8 +/- 0.5 ns, and tau3 = 1 8.0 +/- 3.0 ns. The variation of these three lifetimes as a function o f temperature, emission energy, excitation energy, and eletric field i s studied and the results are interpreted in terms of bound-exciton re combination.